Forms used in forming concrete and other cementitious mixtures are usually made of rigid, reinforced structures having at least one smooth face (finish surface), if a smooth concrete surface is to result from beneath the form. This is important since many types of concrete structure require smooth finishes.
In general, modern construction requires that a wide variety of different, often unconventional, shapes be used in configuring concrete structures. Very often, there is very little standardization, especially when curved shapes are involved. This means that customized concrete forms must be configured for particular situations.
Traditionally wood has been used for curved concrete forms. This has always been awkward and expensive, requiring skilled carpentry, usually at the construction site. Often, such forms are not reusable. Even if reusable, such forms have always been difficult to clean. More recently, sheet metal has been used, as well as wood, to provide smooth curved surfaces for concrete forms. This material is inexpensive and easy to use in manufacturing processes.
Unfortunately, both wood and metal, when used for the facing of concrete forms, have certain drawbacks. Both wood and metal deteriorate due to a number of reasons pertaining to the characteristics of concrete, and usually necessitate frequent refurbishing or replacement of the forms. Further, sheet metal is especially vulnerable because it is easily deformed in an undesirable manner during installation, transport, or the pressure of the concrete pour.
An assembly of multiple precise, irregular, or complex forms, even for small concrete structures, is often a very expensive and awkward activity. Time is lost on the worksite, and inaccuracies are introduced. Cleaning the forms for reuse is also problematical.
One solution has been the use of plastics. However, both the structural stress and chemical corrosiveness of concrete environments render many plastics unsuitable. Also, even the toughest plastics, such as ABS, can be too flexible for the stresses developed in many concrete pour applications. As a result, even if the plastic can be formed into irregular shapes or curves, adequate support of the plastic form is often lacking in conventional systems. Even when adequate support is found, the overall form system configuration is often inadaptable and hard to use.
Accordingly, there is substantial need for a concrete form system that can accommodate multiple curves, and other irregular or customized shapes. The form system should have sufficient mechanical integrity that it can be combined to support a wide variety of different concrete pour shapes. Likewise, the form system should be easy to assemble and clean, and accommodate easy replacement of damaged parts, especially the smooth surfaces that face the finished concrete pour.